Thread tension regulator for textile machines



1965 F. LEMARCHAND 3,223,351

THREAD TENSION REGULATOR FOR TEXTILE MACHINES Filed Feb. 26, 1964 2Sheets-Sheet 1 INVENTOR B7 FRANCIS LEIIHRGll/IND WM W Dec. 14, 1965 F.LEMARCHAND 3,223,351

THREAD TENSION REGULATOR FOR TEXTILE MACHINES Filed Feb. 26, 1964 2Sheets-Sheet 2 -H H 47 4g INV'EMTOR FRHNC! 5 LEMRRCll/W r MW/M W,

United States Patent 6 Claims. hi. 242-154 The present invention relatesto thread tension regulators for textile machines such as, for example,creels, reeling machines, spoolers, winders, false-twist machines, etc.

In the majority of thread tension regulators, the braking of the threadis effected by means of one or a number of devices comprising discs sodesigned that the clamping action thereof increases the tension of thethread on the output side of the regulator. When using devices of thistype, a deposit rapidly forms on the discs as a result of the passing ofthe thread between these latter and calls for frequent dedusting eithermanually or by compressed air, as otherwise the regulator would not workunder satisfactory conditions.

In other known types of regulators, the braking of the thread iseffected by modifying the path of this latter so as to cause tension byproducing a variation in the lengths of the are over which the thread iswound around two cylinders which can be either movable or stationary.These regulators usually comprise a pivotal feeler system which issubjected to the action of a balance weight. \Vhen the speed of movementof the thread is high and, in a more general manner, when the frequencyof variations in thread tension is high, the inertia of the balanceweight adversely affects the stability of tension regulation. Therefrequently take place disturbing pulsations which are a source ofdifficulties in the design of tension regulators of this type, inasmuchas such pulsations are liable to result in damage to the thread.

Finally, tension regulation devices are also known which comprise gridsor traveling rings, that is to say threadbraking devices having a largenumber of points of friction. In the case of devices of this type, it isdiflicult to ensure accurate and progressive tension regulation.Furthermore, in order to balance the thread tension at a number ofdilferent points along its path, it is necessary to apply a relativelysubstantial amount of power. If such power is provided by a balanceweight, the inertia of this latter is detrimental to the good working ofthe regulator, and if this power is supplied by an electromagnet of thelinear action type, the power consumption thereof is relatively high.

The object of this invention is to provide a thread tension regulatingdevice for textile machines which is not subject to the above-mentioneddisadvantages of known devices.

To this end, the thread tension regulator in accordance with the presentinvention comprises in combination: a stationary inlet thread guide, astationary convex shoe having a varying radius and preferably having theshape of a portion of ellipse, a single movable thread guide and astationary outlet thread guide, against each of which in turn the threadwhose tension is to be regulated is intended to pass, the combinedassembly and especially the configurations and relative positions of thestationary shoe and of the path of the movable thread guide being sodesigned and arranged that, when the movable thread guide moves in onedirection along its path under the action of suitable resilient meanssuch as an electromagnetic force which opposes the action produced bythe thread tension on said movable thread guide, this latter produces anincrease in the length of the arc of the shoe against which the threadrubs, whereas said movable thread guide brings about a reduction in thelength of said are when performing a movement in the opposite directionunder the predominant action of the thread tension.

A thread tension regulator of this type is of extremely simpleconstructional design, makes it possible to obtain a very uniform threadtension which can be accurately adjusted to a pre-determined value andwhich does not call for frequent servicing operations either for thepurpose of cleaning, maintenance or re-adjustment.

One object of the invention is to provide a tension regulator whereinthe movable thread guide is mounted at the free end of a lever-arm whichis preferably balanced and the weight of which is as light as possiblewhilst the other end of said leverarm is capable of pivoting about ashaft which is at right angles to the place of the convex profile of theshoe.

Another object of the invention is to provide a tension regulatorwherein the general characteristics of the apparatus including thecharacteristics of the means which apply a restoring force to themovable thread guide are such that, in any angular position of thelever-arm which carries the movable thread guide, the torque which isexerted on said lever-arm by the restoring means is equal to the torqueexerted thereon by the thread tension applied to said movable threadguide.

Yet another object of the invention is to provide a tension regulatorwherein the lever-arm which carries the movable thread guide issubjected to a constant restoring torque which is preferably supplied byan asynchronous motor of the type known as a torque motor, and thedesign of the combined assembly is such that the resultant of thetension oft he run of thread which arrives against the movable threadguide and of the tension of the run of thread which passes out of thislatter accordingly exerts on the lever-arm which carries said movablethread guide a substantially constant torque having a value which isapproximately equal to that of the restoring torque.

Again another object of the invention is to provide a tension regulatorwherein the resilient means for returning the movable thread guide arepneumatic means.

A further object of the invention is to provide a tension regulatorwherein the movable thread guide is coupled to a movable partition wall,one face of which is subjected to atmospheric pressure whilst the otherface is subjected to the pressure of a suitable source of fiuid underconstant pressure.

Again a further object of the invention is to provide a tensionregulator wherein the movable partition wall consists of a vane which ispivotally mounted inside a sealed casing having the shape of a circulararc in which said vane forms two chambers which are respectively incommunication with the atmosphere and with the source of fluid underconstant pressure.

Another object of the invention is to provide a tension regulatorwherein the movable partition wall is constituted by the flexible baseof a capsule, the interior of which is in communication with the sourceof fluid under constant pressure.

The invention will be more readily understood by perusal of thefollowing description and by examination of the accompanying drawingswhich show, by way of example, a few forms of embodiment of threadtension regulators for textile machines according to the invention.

In these drawings:

FIG. 1 is a front view of one form of embodiment electric motor;

FIG.- 2 is a profile v1'ew corresponding to FIG. 1;

FIG. 3 is a front view of another form of embodiment of regulatorwherein the restoring torque is supplied by a pneumatic systemcomprising a pivoting vane;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, thepivoting vane being assumed to be brought back on the plane of thesection;

FIG. 5 is a sectional view taken along line V-V of FIG. 4;

FIG. 6 is a sectional view taken along line VI-VI of an alternative formof regulator wherein the restoring torque is supplied by a manometriccapsule;

FIG. 7 isra sectional view taken along line VI1VII of FIG. 6.

The thread tension regulating device for a textile machine as shown inFIGS. 1 and 2 comprises a casing 1, on one face of which (designatedhereinafter as the front face) are fixed a stationary inlet thread guide2, a stationary outlet thread guide 3 and a convex friction shoe 4having a special shape to which further reference will bevmade below.

A movable thread guide 5 is carried by the free end of an arm 6, theother end of which is integral with a shaft 7 of an asynchronous motoror so-called torque motor, the conventional squirrel cage rotor 8 ofwhich is integral with the shaft 7 and rotates within the stator 9 whichis supplied from any suitable alternating current source, preferably atlow voltage, for example of the order of 24 volts, through supply leadswhich are indicated at 11, 12 in FIG. 2.

The thread 10, the tension of which is to be regulated, passes in turnthrough the stationary inlet thread guide 2,- againstthe: stationaryconvex shoe 4, through the movable thread guide. 5 and the stationaryoutlet thread guide 3.

The arm 6 is capable of taking up practically any of the angularpositions located approximately within the half-circle, the endpositionsof which are indicated at 6and at 6" in FIG. 1. The position 6" isdetermined by astop 15 which limits the amplitude of pivotal movement ofsaid arm inthe direction of application of the thread against the convexfriction shoe 4. When the arm takes up position 6 which is representedin full lines, the three thread guides are substantially in alignmentand the thread is notin contact with the friction shoe; this is anextreme reserve position corresponding to a highly tensioned thread orelse to the position assumed by the leverwhen the restoring motor is notsupplied with current.

The other end position 6" corresponds to a fully slackened thread.

Finally, position 6' corresponds to an intermediate position of normalworking of the apparatus.

The apparatus carries two threaded rods 21, 22 (as shown in FIG. 2) forthe purpose of securing said apparatus to a suitable wall such as thewall 23, for example, by means of clamping nuts 24.

The variable-radius shoe 4 has a profile substantially in the shape ,ofa semi-ellipse between two points A and B which are substantiallylocated in diametrically opposite relation at a certain distance fromthe two summits of the ellipse. This shape is particularly suitable forthe purpose of providing, in the first portion of travel of the arm 6which carries the movable thread guide, a long radius of curvature ofthe surface of the shoe against which the thread 10 is applied, and inthe second portion of travel of the arm, a radius of curvature which isconsiderably shorter with a resulting force of application of the threadagainst the shoe which is considerably greater.

In order to gain a clear understanding of the wholly characteristicadvantage offered by the profile in the shape of a portion of ellipsewhich is given to the shoe 4, it is useful. to point out that, inconventional regulators of this type, the surface of the shoe againstwhich the thread is caused to rub is a cylindrical surface, and thisfeature involves two contradictory requirements between which acompromise has to be adapted.

In point of fact:

(1) In order to ensure a wide range of regulation of the thread tension,it would be necessary to select a relatively large diameter of cylinder.It is desirable, moreover, to ensure that the range of automaticregulation comprises a position in which the thread is not in rubbingcontact with the cylinder, such a position being essential ifmagnification of excess tension is to be prevented.

(2) It would be necessary, on the other hand, to give the frictioncylinder a relatively small diameter in order that the thread can beapplied to the said cylinder under negligible tension and be endowedwith very frequent vibrations as the bobbins are being wound off. Inthis case, it must be made possible to ensure sufiicient pressure persquare millimeter of surface area of thread in contact with the shoe inorder to prevent the creation of a critical some of low pressure inwhich the friction is unstable, whatever the material employed for thefabrication of the cylinder and whatever may be the state of surface ofthis latter and coefficient of friction thereof.

In this connection, it should be pointed out that in such regulatorscomprising a friction cylinder it is impossible, by virtue of their veryprinciple of operation, to maintain a position without friction and atthe same time adopt an arrangement whereby the angle of pull of thethread can be varied without modifying the length of the arc of contactbetween the thread and the shoe.

As a consequence, the displacement of the feeler arm, that is to say ofthe movable thread guide, cannot produce action directly on the unitarypressure of contact of the thread inasmuch as the displacement of saidfeeler arm so acts as to increase or reduce both terms of the ratio P/Swherein P is the total effort of the thread against the convex surfaceand S is the area of the thread which is in contact with said surface.

However, the designs of the prior art do appear to demonstrate that thebest results have been obtained when it has proved feasible, within thelimits of the possibilities offered by friction shoes of cylindricalshape, to cause the feeler to produce action on the pressure applied bythe thread against the convex surface of the shoe rather than on thelengthof the arc of contact.

The shoe in accordance with the invention which has the shape of aportion of ellipse offers a wide range of possibilities, and readilyprovides a radii of curvature in a ratio of '1 to 8.35, for example,which prove entirely satisfactory. By means of this-design, theadvantages of cylin-v ders having a large diameter can be turned toprofitable. account while at the same time retaining the advantages ofcylinders having a small diameter.

It follows from the foregoing in particular that the followingadvantages can be obtained in combination:

Position of zero friction in the case of excess tension, this being theposition shown in full lines in FIG. 1 in which can be seen the thread10 passing through the three aligned thread guides 2, 5 and 3 withoutrubbing against the shoe 4.

Very wide range of adjustment of the thread tension.

Direct action on the value of the unitary pressure of the thread againstthe shoe in the second portion of the angular travel of the movablethread guide 5 and in the Zone of small radius of the shoe by. varyingthe angle of pull, that is to say the angle made with the surface of theshoe at its point of contact with this latter by the portion of threadcomprised between the thread guide 5 and said shoe; this pres-sure isthus varied without substantial variation in the total surface area ofthread which engages the shoe in View of the fact that said surface areaalready corresponds to the entire long-radius portion of the shoestarting from the point A, and that the length of the short-radiusportion of the shoe which is covered by the thread varies to a verysmall extent during these pivotal movements of the feeler arm.

Very short lever-arm of the feeler 6, although the radius of curvatureof the large convex surface of the shoe is two to five times greaterthan in the majority of conventional regulators.

Low inertia as a result of the small length of the arm 6 which carriesthe movable thread guide, thus also reducing the power to be suppliedthereto.

Angular travel greater than 180 without requiring anyeffort-multiplication system, thereby ensuring a progressivetension-regulating action and a range of automatic compensation, theflexibility of which makes it possible, without any need for manualre-adjustment of the regulator, to work textile threads of verydifferent kinds or diameters.

Straight path of travel of the thread, which passes without frictionagainst the shoe and against the thread guides when the feeler arm isnot actuated by the torque motor, thus providing an advantage which haslong been sought by users.

Substantial reserve of thread which can be released in the event ofexcess tension. In fact, when the feeler arm 6 passes from the positionshown in full lines in FIG. 1 to the intermediate position 5' which isshown in chaindotted lines, then to the opposite end-position 5" whichis also shown in chain-dotted lines, a substantial reserve of thread isthus formed.

Small overall size and very great simplicity of the apparatus as awhole.

The combined assembly is so designed and arranged that, depending on theexact form of the path which is followed by the movable thread guide 5and which is a curve having the shape of a circular arc, on theconfiguration of the convex shoe which, in this example, is a curvehaving the shape of a portion of ellipse, on the relative position ofthese two curves, and on the va ue of the constant torque supplied bythe torque motor, the resultant of the tension of the run of threadwhich arrives at the movable thread guide 5 and of the tension of therun of thread which passes out of this latter produces, by pulling onthe arm 6, a torque which is equal to the resilient torque supplied bythe restoring-torque motor, this being the case irrespective of theangular position of said arm.

The operation of the apparatus is therefore as follows: in steady-stateoperation, the thread rubs on the shoe 4 (FIG. 1). If the tension of thethread 10 on the input side of the regulator has a tendency, forexample, to slacken off, the torque exerted by the thread becomes lowerthan the restoring torque of the motor by reason of the friction forcewhich is applied against the shoe, with the result that the arm 6performs a pivotal movement in the direction of the arrow f1.Consequently, the length of the arc of the shoe 4 with which the threadis in rubbing contact increases until such time as the torque exerted onthe arm 6 by the increasing tension of the thread once again balancesthe value of the torque supplied by the restoring-torque motor. Theapparatus accordingly becomes stabilized in this new position.

Conversely, if the tension of the thread 10 on the input side of theregulating apparatus were to increase, the action produced by the threadtension on the arm 6 would become preponderant over that of therestoringtorque motor, with the result that the arm 6 would accordinglyperform a pivotal movement in the direcion opposite to that of the arrowf1, thereby resulting m a reduction in the friction force applied by thethread against the shoe and consequently a reduction in the torqueexerted on said arm 6 by the thread. Said arm would thus pivot andconsequently reduce the length of the arc of rubbing friction of thethread against the shoe until the torque which results from the tensionof the thread has been reduced to a value equal to the value of thereference torque of the restoring-torque motor. The

apparatus will again be stabilized in this new position until such timeas there takes place a further variation in the tension of the thread onthe input side of the regulator.

The arm 6 is as light in weight as possible and, in addition, thepivotal assembly is statically balanced about the geometrical axisthereof. To this end, for example, the arm 6 is fixed on the shaft 7 ofthe motor through the intermediary of a member which is provided with aboss 13 on that side which is located opposite to the lever-armrelatively to the pivotal axis.

In order to set the thread tension at any desired value, it is merelynecessary to regulate the torque of the restoring-torque motor to thecorresponding value. This adjustment can accordingly be made from adistance by giving a corresponding value to the excitation current ofthe motor. Consequently, the thread tension can be remote-controlledsimultaneously in all the regulating devices at the same time and can beregulated and modified at will, for example as a function of the threadfeed during a thread winding operation.

In FIGS. 3 to 5, an alternative form has been shown wherein therestoring torque of the feeler arm 6 is carried out by means of apneumatic device comprising a vane 31 mounted within a casing 32 havingthe shape of a circular arc and pivoted on a shaft 7a which is integralwith the feeler arm 6. The casing 32 carries the stationary inlet threadguide 2 and the stationary outlet thread guide 3 as well as the convexelliptical shoe 4 which has the same configuration as that of the formof embodiment of FIGS. 1 and 2.

The vane 31 divides the interior of the casing 2 into two chambers 32a,32b fitted respectively with a pipe 34 which is connected to a suitablesource of gas under pressure and a pipe 35 which opens directly int-othe atmosphere.

The torque which must be applied to the feeler arm 6 is supplied by thedifference in the pressures which prevail within the two chambers 32aand 32b of the casing and which are exerted on the two opposite faces ofthe pivoting vane 31. The flow of air is determined by the small leakagewhich occurs between the chamber 32a and the chamber 32b, along thebaflles provided on the external edge of the vane 37 and on an arcuateportion 38 which forms part of the casing and which is located againstthe cylindrical hub of said vane.

The supply of gas under pressure, which is preferably compressed air, iseffected by any suitable means of conventional type such as that whichhas been represented diagrammatically in FIG. 5 and which comprises anelectric motor 41, an air compressor 42 which is driven from said motor,an air reservoir 43 connected to the outlet nozzle of the compressor 42,and a pressure-reducing valve 44 which is connected to the outletorifice 45 of the compressed air reservoir 43 and which determines thepressure of compressed air delivered to a general supply pipe 46 whichis connected to the nozzle 34 through a branch pipe 47 whilst otherbranch pipes such as 47a, 4712, etc., serve to feed other regulators ofsimilar design. A pressure gauge 48 indicates the pressure in thegeneral supply pipe 46.

The operation of said regulator is the same as that described inreference to the form of embodiment of FIGS. 1 and 2, the onlydifference being that the restoring torque to which the feeler arm 6 issubjected is supplied by the pneumatic system described above instead ofbeing supplied by a torque motor.

The compressed air at low pressure which is intended to supply thepneumatic device calls for a lower consumption of power than that whichis required by an electric torque motor while at the same time supplyinga maximum torque of substantially the same value and a responsivenesswhich is comparable to that of the form of embodiment in which therestoring torque is supplied by a torque motor.

In FIGS. 6 and 7,.there is shown an alternative form of embodimentwherein the pneumatic means for restoring or returning the movablethread guide no longer comprise a pivoting vane but comprise instead acircular flexible diaphragm 51, the edge of which is clamped over the.periphery of a capsule 52 provided with a pipeconnection 53 for thepurpose of connecting said capsule to a source of fluid under constantpressure. The central portion of the flexible diaphragm 51 isstrengthened by two discs 54, 55 which are secured respectively againstthe two faces of said central portion of the diaphragm, for example bymeans of a rivet 56.

The manometric capsule 52 is fixed flat in the bottom of a box 57 onwhich are supported, as in the form of embodiment of FIGS. 3 to 5, thestationary inlet thread guide 2'and stationary outlet thread guide 3 aswell as the movable thread guide 5 which is integral with an arm 6awhich is mounted on a pivot-pin 7b, said pivot-pin.

being journalled in two bearings 61, 62secured to a support 63 which isintegral with the box 57. Said box additionally carries the. convexelliptical shoe 4;

The kinematic connection between the pivot-pin 7b of the movable threadguide Sand the diaphragm 51 of the manometric capsule consists of abevel pinion 65 which is integral with the pivot-pin 7b and engaged witha corresponding toothed sector 66 which is made fast with a shaft 67,the two ends of which are pivotally mounted in two lugs 68, 69 formingpart of'the casing 57, the direction of the shaft 67 being at'rightangles to that of the shaft of the pivot-pin 7b which supports themovable thread guide. The toothed sector 66 forms one piece with anarm.71, the extremity of which is. adapted to bear against the rivet 56which is secured to the cena tral portion of the diaphragm.

The outer face of the diaphragm 51 is accordingly subjected toatmospheric pressure whilst the inner face thereof'is subjected to thepressure of the source of fluid under constant pressure with the resultthat this latter exerts the desired restoring torque on the movablethread guide 5 through the intermediary of the drive system describedabove.

The operation of the regulator which has just been described is the sameas that of the form of embodiment of FIGS. 3 to 5, the only differencebeing that the restoring torque of the movable thread guide 5 issupplied by different pneumatic means.

It will be understood that the invention is not limited to the forms ofembodiment which have been described and illustrated andthat a largenumber of modifications can be made therein without consequentlydeparting either from the scope or the spirit of the invention.

It accordingly follows, for example, that in the form of embodimentdescribed, the stationary inlet and outlet thread guides form part ofthe regulating apparatus but can equally well be incorporated in thetextile machine on which said apparatus is mounted.

What I claim is:

1. A thread tension regulating device comprising: a casing, a stationaryinlet thread guide secured to said casing, a convex shoe secured to saidcasing and having a long radius portion adjacent said inlet thread guideand a shorter radius portion remote from said thread guide, a movablethread guide pivotally mounted on said casing, a stationary outletthread guide secured to said casing, said movable guide beingoperatively associated and located with respect to said convex shoe sothat thread threaded successively through said inlet guide, said movableguide and said outlet guide will frictionally engage an arcuate portionof said convex shoe which is longer and longer as said movable threadguide is pivoted more and more in a predetermined direction, and meansmounted in said casing for resiliently urging said movable thread guidein said predetermined direction with a constant torque adapted to alwaysbalance the torque exerted by the thread tension upon said movablethread guide.

2. A device accordingto claim 1, wherein said convex shoe issubstantially in the shape of half an ellipse between two points thereofsubstantially diametrically opposed and located at a predetermineddistance from the end of the major axis of said ellipse.

3. A device according to claim 1, wherein said means for resilientlyurging said movable thread guide is an electric torque motor.

4. A device according to claim 1, wherein said means for resilientlyurging said movable thread guide are pneumatic means.

5. A device according to claim 4, including a partition which is movablein said casing, said partition sealingly dividing said casing into twochambers, one of said chambers being in permanent communication with theatmosphere while the other is adapted to be connected to a suitableconstant pressure fluid source.

6. A device according to claim 5, wherein said partition is constitutedby a vane pivotally mounted in said casing, said casing being at leastpartially cylindrical.

References Cited by the Examiner UNITED STATES PATENTS 1,475,855 11/1923Murdock. 2,331,261 10/ 1943 Wholton 242-154 FOREIGN PATENTS 523,5807/1940 Great Britain. 833,425 4/1960 Great Britain. 1,334,485 7/ 1963France.

JORDAN FRANKLIN, Primary Examiner.

1. A THREAD TENSION REGULATING DEVICE COMPRISING: A CASING, A STATIONARYINLET THREAD GUIDE SECURED TO SAID CASING, A CONVEX SHOE SECURED TO SAIDCASING AND HAVING A LONG RADIUS PORTION ADJACENT SAID INLET THREAD GUIDEAND A SHORTER RADIUS PORTION REMOTE FROM SAID THREAD GUIDE, A MOVABLETHREAD GUIDE PIVOTALLY MOUNTED ON SAID CASING, A STATIONARY OUTLETTHREAD GUIDE SECURED TO SAID CASING, SAID MOVABLE GUIDE BEINGOPERATIVELY ASSOCIATED AND LOCATED WITH RESPECT TO SAID CONVEX SHOE SOTHAT THREAD THREADED SUCCESSIVELY THROUGH SAID INLET GUIDE, SAID MOVABLEGUIDE AND SAID OUTLET GUIDE WILL FRICTIONALLY ENGAGE AN ARCUATE PORTIONOF SAID CONVEX SHOE WHICH IS LONGER AND LONGER AS SAID MOVABLE THREADGUIDE IS PIVOTED MORE AND MORE IN A PREDETERMINED DIRECTION, AND MEANSMOUNT-